請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60964
標題: | 成長在砷化鎵基板的矽摻雜磷化銦鎵之材料特性研究 Study on the Material Properties of Si-doped InGaP grown on GaAs Substrate |
作者: | Hong-Shen Guo 郭泓伸 |
指導教授: | 林浩雄 |
關鍵字: | 同步輻射,價力場模型,電漿子聲子耦合模態, synchrotron radiation source,valence force field model,Plasmon-LO-Phonon couple mode, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本文係針對以有機金屬化學氣相沉積法(MOCVD, Metal-organic Chemical Vapor Deposition)所成長之不同矽摻雜濃度的磷化銦鎵所做之光學特性分析。我們以同步輻射光源進行EXAFS量測分析,配合IFEFFIT軟體對吸收頻譜進行正規化與座標空間轉換處理,並分別建立磷中心與銦中心的立方晶散射路徑模型,擬和後可得到一系列條件參數並以鍵長變化判斷其有序排列程度。對CA8815L系列樣品而言,熱退火處理將使有序排列程度改變,EXAFS分析亦可清楚顯示。
我們進一步以價力場模型(Valence force field model)對不同有序排列程度下的磷化銦鎵結構進行分析,透過建立一4×4×4單位晶格大小共包含512顆原子的超晶格,並計算其收斂狀態的畸變能,分析可知熱退火處理後將使磷化銦鎵的有序排列程度降低,這也可以解釋我們在EXAFS分析所得到的結果。 另外我們以拉曼散射光譜來判斷磷化銦鎵結構特性,對有外部摻雜的極性半導體而言將有一獨特的電漿子聲子耦合模態。當摻雜效應所造成的電子濃度高於1018cm-3時,其中的L-模態將收斂在330cm-1附近,因此我們透過不同散射形態的拉曼選擇律定義出其存在。在360cm-1與380cm-1處我們亦觀察到應該因耦合而消失的LO聲子模態,其訊號可能來自於表面缺陷複合電子後所形成的表面空乏區,在此區域將不會有電子屏蔽效應,因此我們仍可量測到來自LO聲子模態的訊號。另外對CA8815L系列而言,其拉曼頻譜整體訊號峰值位置皆有一往低波數方向的微小偏移,故可由此說明熱退火處理的確會造成有序排列程度的降低。 In this thesis, we mainly investigate the optical properties of Si-doped InGaP/GaAs grown by MOCVD. We examine the lattice structure by EXAFS with synchrotron radiation source. We first normalize the absorption spectrum and transform the coordinate from K-space to R-space with Athena software. Then we build an indium center cubic cell to simulate the scattering path of InP. Finally we will get a series of InP bond length, and we may judge the degree of order of different doping levels. For Si-doped InGaP CA8815L series, we clearly observe that annealing lowers the degree of order in IFEFFIT fitting results. Furthermore, we build a 4×4×4 superlattice structure with 512 atoms for different order parameters by Valence Force Field Model to calculate distortion energy. When the distortion energy converge to minimum, the atom sites may represent a stable lattice structure. Annealing may destroy the order structure, which is well agreed with our result of EXAFS analysis. On the other hand, we report the Raman scattering of the Si-doped InGaP. The Raman spectrum shows plasmon LO-phonon (PLP) coupled mode for doped semiconductor. The wavenumber k of the L- mode will increase with electron concentration, and it may converge to 330cm-1 when n>1018cm-3. At 360cm-1 and 380 cm-1 we observe an abnormal behavior of LO phonon mode which should not appear due to screen effect. The unscreened LO mode is attributed to the surface depletion region, where defects trap electrons forbidding screen effect. For Si-doped InGaP CA8815L series, the -2cm-1 shift of Raman peak indicates that annealing lowers the degree of order. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60964 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-101-1.pdf 目前未授權公開取用 | 3.69 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。